Brackish Water Reverse Osmosis Research Articles

Optimization of interfacial polymerization to fabricate thin-film composite hollow fiber membranes in modules for brackish water reverse osmosis

The development of commercial-scale thin-film composite (TFC) hollow fiber membranes and modules for reverse osmosis (RO) has been lagging behind spiral wound TFC flat-sheet membranes and modules for many years. The delay arises from the challenges of synthesizing a defect-free polyamide selective layer on hollow fibers in modules. In order to solve this problem, a novel interfacial polymerization method is presented in this work to fabricate 1-inch TFC hollow fiber membrane modules for RO applications. By circulating the m-phenylenediamine (MPD) solution on the lumen side under a positive pressure and circulating the trimesoyl chloride (TMC) solution at the atmosphere pressure, a strong, uniform and defect-free polyamide selective layer is formed on the inner surface of hollow fiber membranes in modules. Under pressure, not only MPD monomers are evenly distributed on the inner surface of each hollow fiber substrate in modules, but also sufficient MPD monomers can retain in the substrate pores for further reaction with TMC monomers. The best RO performance obtained by this newly developed TFC hollow fiber membrane module has a water permeability of 4.49 L m−2 h−1 bar−1 and a NaCl rejection of ~99%, using a feed solution of 1000 ppm NaCl under a transmembrane pressure of 20 bar. The novel interfacial polymerization method may provide useful insights to fabricate TFC hollow fiber membrane modules for desalination of brackish water.

Treatment of Brackish Water RO Brine via Bipolar Membrane Electrodialysis

Due to the demand for acid and base in brackish water reverse osmosis (RO) desalination plants located in remote areas and the difficulty of transporting acid and base, bipolar membrane electrodial...

Partial Desalination of Saline Groundwater: Comparison of Nanofiltration, Reverse Osmosis and Membrane Capacitive Deionisation

Saline groundwater (SGW) is an alternative water resource. However, the concentration of sodium, chloride, sulphate, and nitrate in SGW usually exceeds the recommended guideline values for drinking water and irrigation. In this study, the partial desalination performance of three different concentrated SGWs were examined by pressure-driven membrane desalination technologies: nanofiltration (NF), brackish water reverse osmosis (BWRO), and seawater reverse osmosis (SWRO); in addition to one electrochemical-driven desalination technology: membrane capacitive deionisation (MCDI). The desalination performance was evaluated using the specific energy consumption (SEC) and water recovery, determined by experiments and simulations. The experimental results of this study show that the SEC for the desalination of SGW with a total dissolved solid (TDS) concentration of 1 g/L by MCDI and NF is similar and ranges between 0.2–0.4 kWh/m3 achieving a water recovery value of 35–70%. The lowest SECs for the desalination of SGW with a TDS concentration ≥2 g/L were determined by the use of BWRO and SWRO with 0.4–2.9 kWh/m3 for a water recovery of 40–66%. Even though the MCDI technique cannot compete with pressure-driven membrane desalination technologies at higher raw water salinities, this technology shows a high selectivity for nitrate and a high potential for flexible desalination applications.

Thin-film nanocomposite membranes incorporated with defective ZIF-8 nanoparticles for brackish water and seawater desalination

In this work, a series of defective ZIF-8 (dZIF-8) nanoparticles with tuneable inner defects have been synthesized and successfully incorporated into the polyamide-based thin-film nanocomposite (TFN) membranes for brackish water and seawater desalination. This is the first attempt to use dZIF-8 nanoparticles as nanofillers in TFN membranes. Additional inner porosity of dZIF-8 nanoparticles endows the membranes with additional pathways for water molecules. Thus, the newly developed TFN membranes have higher separation performance for brackish water reverse osmosis (BWRO) desalination than the normal ZIF-8-incorporated TFN membranes. In addition, the influences of dZIF-8 loading on membrane properties and separation performance have been investigated. At a loading of 0.15 wt% dZIF-8 nanoparticles in the oil phase, the TFN membrane shows a water permeance of 2.61 L m-2 h-1 bar-1 (LMH bar-1) and a salt rejection of 98.6% for brackish water desalination at 20 bar. This water permeance is 52% higher than the pristine thin-film composite (TFC) membrane while the salt rejection is well maintained. Moreover, a steady water flux above 38 LMH is obtained when using seawater of 32000 ppm NaCl as the feed at 50 bar.

Design and performance of small-scale reverse osmosis desalination for brackish water powered by photovoltaic units: a review

The reverse osmosis (RO) water desalination system powered by the photovoltaic (PV) unit is commonly used to produce drinking water due to their reasonable price. This review focused to display different designs of small-scale PV powered brackish water RO (PV-BWRO) systems that were installed to improve the water productivity at remote areas. The configuration of BWRO units, which determined the operating cost, permeate flow and amount of rejected water, is of great concerns in this work. The specific energy consumption (SEC), total capital cost and water production cost are also analysed to display the feasibility of application of PV unit for small-scale BWRO desalination system. The single-stage configuration was suitable for most of small-scale BWRO systems owning high recovery rates (i.e., higher than 50%). The PV solar system pairing with batteries was not recommended at production capacities below 5 m3 for their high cost and short lifetime. Independently operated PV-BWRO systems required the highest capital cost while produced the lowest operating and overall production costs compared to hybrid systems.

Conceptual arrangement and basic design of drinking water reverse osmosis desalination plants

To propose a conceptual arrangement of reverse osmosis desalination plants, four comprehensive decision algorithms and a software are developed. Typically, commercial software predict the performance of the reverse osmosis membranes based on their pre-determined configuration; however, the developed decision algorithms and the developed software in this study have the capability of introducing the conceptual arrangement of pretreatment units, reverse osmosis membranes, and energy recovery devices for both seawater and brackish water reverse osmosis plants. To perform a comprehensive study, alongside the developed software and the decision algorithms, both design considerations of the required equipment in pretreatment units and mathematical modeling of reverse osmosis membranes are included. Finally, to validate the accuracy of the developed decision algorithms and the software, four installed reverse osmosis desalination plants for producing drinking water from seawater and brackish water feeds are investigated. The algorithmic proposed plants for all four cases were in close agreement with the implemented industrial cases and World Health Organization standards.

Sorption of recalcitrant phosphonates in reverse osmosis concentrates and wastewater effluents - influence of metal ions.

Magnetic microparticles functionalized with tailored ZnFeZr oxyhydroxide adsorbent were used for the reversible sorption of orthophosphate and recalcitrant organo-phosphonates from wastewater. The loaded particles were harvested magnetically from water, regenerated in an alkaline solution and reused numerous times. The applicability of the technology to treat brackish water reverse osmosis concentrates was tested under controlled synthetic conditions by investigating the influence of typical metals (Ca2+, Pb2+, Cu2+) on the removal of common phosphonates (HEDP, NTMP, EDTMP), and vice versa. When present at equimolar concentrations, metal cations enhanced the adsorption of phosphonates and were co-adsorbed at pH 4.0-4.5 (with removals of 83-93% for Pb2+ and 53-73% for Cu2+), likely through ternary complex formation. In the absence of metals, at pH > pHPZC ∼ 7 (the material point of zero charge), a drop in adsorption efficiency was observed for orthophosphate and all phosphonates. Thus, at pH 7, an increased adsorbent dose (>0.1 g/L) was necessary to remove 1 mg/L NTMP-P in 30 min. The reusability and effluent polishing potential of the ZnFeZr particles was demonstrated in a pilot test with municipal wastewater throughout 55 adsorption/desorption cycles without any drop in performance. Consistent removal of the non-reactive phosphorus species to ultra-low concentrations (<0.05 mg/L Ptot) and complete orthophosphate elimination (<0.005 mg/L PO4-P) was maintained under optimal conditions.

Performance evaluation of a medium-scale industrial reverse osmosis brackish water desalination plant with different brands of membranes. A simulation study

Brackish water can be considered an important source of fresh water, via desalination, especially for arid districts. Reverse Osmosis (RO) process has been successfully used to produce fresh water from brackish water sources. However, there is still the challenge of improving the performance of multistage RO desalination plants. From the selection of the RO configurations to the selection of the appropriate type of membranes and the operating conditions at the end determines the performance of RO process in terms of recovery, salt rejection, energy consumptions and ultimately the cost of production of freshwater. Using model-based simulation, this work attempts to investigate the most suitable types of membranes for an industrial scale RO plant from a set of different membrane brands that would attain the highest-performance at lowest specific energy consumption (SEC). As a case study, we considered a multistage multi-pass medium-scale RO plant (1200 m3/day) of Arab Potash Company (APC, Jordan) which produces high quality water for the boilers after pre-treatment stage. The simulation results confirmed that employment of the Filmtec BW30LE-440 would increase water recovery by about 22% besides reducing the product salinity and SEC by about 15% and 10%, respectively compared to the existing membrane.

Smart system management and techno‐environmental optimal sizing of a desalination plant powered by renewables with energy storage

The present study assessed the performances of a brackish water reverse osmosis desalination unit powered by (PV/Wind/Battery) system with hydraulic storage. The hybrid renewable energy system and the reverse osmosis desalination plant were modeled for a specific site in southern Tunisia using real meteorological and water consumption data for 1 year. A total of 8760 simulations were treated under a dynamic simulator coupled to a smart energy management strategy to reach the hourly water load demand. Although the recognized reliability of the hybrid renewable sources compared to one- power source, their design may still critical. Therefore, in this paper, the authors suggest applying the methodology of optimizing the presented unit using an integrated systemic meta-modeling which is built through the design of experiments tool and defined by an equation involving the decision variables of the optimization as its parameters. This equation outlines the objects of the optimum sizing. The selected optimal design of the proposed unit is predicted by the genetic algorithm NSGA-II based on minimizing two objectives in conflict: Embodied energy and hydraulic loss of power supply. The CPU time of the NSGA-II optimization via the meta-model reached only 15 minutes of treatment (with one day to build the design of experiments) compared to the classic optimization via dynamic simulation. The results of the optimum sizing show that it is possible to consider a low water shortage rate (0% ⩽ LPSP-H < 5%) for a marginal variation of embodied energy rate which does not exceed (7%).

Energy, exergy, exergoeconomic, and environmental (4E) and carbon footprint analysis of coupling the various energy recovery devices with seawater and brackish water reverse osmosis desalination

Energy, exergy, exergoeconomic, and environmental (4E) and carbon footprint analysis of coupling the various energy recovery devices with seawater and brackish water reverse osmosis desalination

Treatment of brackish water reverse osmosis brine using only solar energy

Nanophotonics enhanced solar membrane distillation as a solar-powered treatment is implemented for treating reverse osmosis (RO) brine. The proposed process efficiently uses sunlight to desalinate RO brine and maximize its water recovery.

Novel Dynamic Designs for Ultra-High Recovery Waste and Brackish Water RO Desalination

Novel Dynamic Designs for Ultra-High Recovery Waste and Brackish Water RO Desalination

Highly permeable thin film composite hollow fiber membranes for brackish water desalination by incorporating amino functionalized carbon quantum dots and hypochlorite treatment

A novel strategy has been demonstrated to synergistically improve the separation performance of thin film composite (TFC) hollow fiber membranes for brackish water reverse osmosis (BWRO) desalination. It consists of two steps. Firstly, a series of amino functionalized carbon quantum dots (CQDs) were synthesized and incorporated into the polyamide layer of TFC membranes. The modified TFC membrane with the optimal amino functionalized CQDs has a pure water permeability (PWP) of 5.50 LMH/bar and a NaCl rejection of 98.0% against a 2000 ppm NaCl feed solution at 15 bar. Comparing with the unmodified TFC membrane, the modified TFC membrane has a 42.1% higher PWP without compromising the salt rejection. Then the modified TFC membrane was treated by a sodium hypochlorite solution at different concentrations. Chlorine was bonded to the polyamide layers, enhancing their repulsion against charged solutes and making the polyamide network less cross-linked. As a result, both PWP and NaCl rejection of the TFC membranes could be improved. After being treated with a sodium hypochlorite aqueous solution at 4000 ppm for 3h, the aforementioned modified TFC membrane displays a PWP of 10.13 LMH/bar and a NaCl rejection of 98.9% against a 2000 ppm NaCl solution at 15 bar, which demonstrates a great potential for brackish water desalination. This study may mark a milestone for the development of future BWRO membranes based on the use of amino functionalized CQDs and hypochlorite treatment.

Process for high recovery treatment of brackish water reverse osmosis concentrate

A brackish water reverse osmosis concentrate consisting of 4170 mg/L total dissolved solids (TDS) and a gypsum saturation ratio (SR) of 1.52, was treated to a volumetric recovery of 96.5% in a total recycle process utilising hydrated lime and CO2 induced precipitation reactors and nanofiltration (NF) separation units. A chemical model that incorporates PHREEQC COM v3 and the pitzer.dat database was developed to verify the achieved volumetric recovery in terms of the experimental process parameters. The model showed that a NF concentrate purge of 1.2% would have been required to sustain the cycled up mass balance. The NF feed and concentrate streams cycled up to 16,750 and 32,900 mg/L TDS respectively. The experimentally achieved SR in the secondary NF (SNF) concentrate was 2.37. The generally accepted gypsum SR limit for effective scale suppression through antiscalant addition is <2.5–4.0. A high volumetric recovery at an acceptable gypsum SR in the SNF was thus attained.

Systemic design and energy management of a standalone battery-less PV/Wind driven brackish water reverse osmosis desalination system

This work investigates a small-scale reverse osmosis desalination system dedicated for off-grid communities lacking freshwater. This system, constituted of motor-pumps, desalination process and hydraulic network (pipes and valves), is powered by hybrid photovoltaic-wind turbine source. It exploits hydraulic storage in water tanks filled when renewable energy is available instead of electrochemical storage. Such specificity makes the power/freshwater supply a challenging issue for these communities. To maximize freshwater production of this autonomous system, a “systemic design approach” integrating couplings between architecture, sizing, and energy management is proposed. According to the specific system architecture and its component sizing, a specific quasi-static model-based energy management strategy (EMS) is developed. In this regard, the influence of the main component sizing on the system energy efficiency and the EMS performance is analyzed. This study proved the strongly coupling between power/water management and pump sizing. According to the iterative process of the systemic design approach, simulation results showed that the EMS objective is reached by increasing the brackish water storage tank capacity and improving the system energy efficiency. The latter is achieved by choosing the pumps-combination composed of three pumps having the lowest rated powers (0.37 kW/0.37 kW/1.5 kW), but offering higher energy efficiency over other analyzed pumps-combinations.

Modelling framework for desalination treatment train comparison applied to brackish water sources

Desalination is known to have considerable energy, economic, and environmental impacts. Treatment trains are receiving increased interest for their potential to meet produced water standards while both minimizing impacts and increasing the range of eligible input salinities. However, determining which technologies to combine and predicting their performance is both difficult and case specific. This research will present a unique hybrid-modelling framework (DESALT) for evaluating and comparing desalination treatment trains based on the same customizable inputs. This comprehensive discrete-based approach generates treatment trains and then systematically evaluates them using physics-based evaluation methods that are reflective of changes in operating conditions. DESALT also accounts for technology limitations, product water requirements, and user preferences. The modelling outputs are filtered using a combination of a Pareto front analyses and DEA decision support. The result is a list of eligible and preferred treatment trains with their corresponding operating conditions. The framework's performance was tested by applying two different technologies (electrodialysis and brackish water reverse osmosis) to a brackish water case study. While the methodology was able to capture the trade-offs between treatment trains and individual technologies, the results are highly reliant on the accuracy of the evaluation methods used.

Design, modelling and optimisation of a batch reverse osmosis (RO) desalination system using a free piston for brackish water treatment

Batch RO is a concept for achieving the minimum possible energy consumption in desalination, even at high recoveries. We present a batch RO design that operates cyclically in two alternating phases. The system uses a free piston, housed in a pressure vessel, to transfer pressure from the feed fluid to the recirculating fluid. No complete design procedure for this configuration currently exists. To fill this gap, we present a systematic model based on justified assumptions. The specific energy consumption (SEC) is broken down into contributions from the feed pump, recirculating pump, and auxiliary loads. The calculation of feed pump SEC includes three non-ideal correction factors: concentration polarisation, longitudinal concentration gradient, and salt retention. The model requires only the solution of explicit algebraic equations, without need of specialised numerical techniques, and is implemented in a simple 3-step procedure. The model is applied to an example involving desalination of brackish water using an 8-inch spiral-wound RO module. The design parameters are explored and optimised in a sensitivity analysis. The results show that the optimised batch RO at 80% recovery can produce fresh water with low-energy consumption, achieving 2nd law efficiency of 33.2% compared to 10–15% for conventional brackish water RO.

Operational strategies for brackish water desalination plants in island regions of South Korea

Based on the operational data from the Korea Water Resources Corporation (K-water), this study aimed to reduce the operation and maintenance (O&M) costs for 20 brackish water desalination plants in the island regions of South Korea. In addition, brackish water reverse osmosis (BWRO) and low-pressure reverse osmosis (LPRO) membranes were compared and evaluated in terms of reduction in specific energy consumption (SEC) for an island brackish water desalination plant. The high labor costs and plant breakdown accounted for most of the operating losses with low operation rates (less than 60% in 19 plants) and low water flow rates (less than 90% in 15 plants). Thus, in order to reduce the O&M costs of island region desalination plants, it was essential to optimize the plant design while increasing the operation and water flow rates. In particular, installation of the LPRO membrane has shown potential for SEC improvement (approximately 16%) due to high pressure pump optimization and high recovery. These operational strategies for island region desalination plants are applicable alternatives in terms of reduction in O&M costs and SEC.

The techno-economic case for coupling advanced spacers to high-permeance RO membranes for desalination

Innovations in advanced materials in recent years have produced great improvements in the permeance of reverse osmosis (RO) membranes for desalination. This work presents a simplified techno-economic analysis for a representative advanced spacer and a high-permeance RO membrane under typical feed and operating conditions. The results agree with common trends for specific energy consumption (SEC). For high-permeance membranes, advanced spacers are more effective than conventional spacers in improving flux in the region close to the inlet, due to a fast decrease in Reynolds number along the channel. The total cost for seawater RO (SWRO) and brackish water RO (BWRO) could be reduced by 7.5% and 32%, respectively by increasing the membrane permeance to 10 L/m2.h.bar regardless of the spacer type used. However, as feed velocity has negligible effects on total cost for high-permeance membrane systems, further cost reductions with larger membrane permeances are limited due to significant concentration polarisation and lower mass transfer. Nevertheless, when operating SWRO at constant recovery, those levels of cost reduction can be achieved with an advanced spacer at half of that membrane permeance value. This highlights that more cost-effectiveness can be gained by improving the spacer efficacy than by increasing membrane permeance.

Long-term intermittent operation of a full-scale BWRO desalination plant

The use of renewable energy sources (RES) to power reverse osmosis (RO) desalination plants is a promising option for remote communities that face water scarcity. One drawback, however, is that the plants are generally obliged to operate intermittently due to the nature of the RES, which can reduce RO system performance in terms of production, salt rejection and energy consumption. This work analyses the long-term performance of a full-scale brackish water reverse osmosis (BWRO) desalination plant that has been working under intermittent operating conditions for 14 years (~9 h d−1). The plant has two stages, a 2:1 arrangement and five spiral wound membrane elements per pressure vessel (Filmtec™BW30-400). The feed water is pumped from a groundwater well. The feed flow and water flux recovery remained practically constant (416 m3 d−1 and around 65% respectively) over the 14-year period. The plant uses antiscalant dosing (5 mg L−1) and two cartridge filters in series (25 and 5 μm) as a pre-treatment. Rinses are carried out before shut-downs. Feedwater conductivity, permeate conductivity, feed pressure, pressure drop, permeate flow, and feed flow operating data were collected. The results show a decrease of about 50% in the average water permeability coefficient and an increase in specific energy consumption from 1.82 to 2.21 kWh m−3. The results provide useful information about the behavior of BWRO desalination systems under intermittent operating conditions and should be taken into account when designing RES-powered BWRO desalination plants.